Separation and Identification of Minerals from Lignites

Methods for Characterization of Inorganic and Mineral Matter in Coal: A Critical Overview

“…Physical Separations. The density fractionation of crushed coal in heavy liquids (chemically inert to coal constituents) is a very important procedure for the concentration and subsequent characterization of IM and MM in coal. ,,,,,,,,− For example, the coal fractions separated by heavy liquids with density <1.6, 1.6−2.9, and >2.9 g/cm 3 are normally the most useful because they are related, respectively, to the enrichment of OM, some rock-forming minerals and phases (quartz, feldspars, clay and mica minerals, calcite, magnesite, dolomite, ankerite, gypsum, volcanic glass), and heavy accessory minerals (As, Cu, Pb and Zn sulfides, Al, Cr, Fe and Ti oxides, zircon, garnet, Fe sulfates, barite, celestine, anglesite, witherite, strontianite, smithsonite, apatite, monazite, xenotime, scheelite) plus certain heavy Fe sulfides and carbonates (pyrite, marcasite, pyrrhotite, siderite). Naturally, in most cases these minerals are finely dispersed in coal and intimately associated with OM in particles and they are difficult to separate in heavier concentrates and commonly pass to lighter fractions (clay minerals, sulfates, carbonates, and occasionally sulfides).…”

“…Naturally, in most cases these minerals are finely dispersed in coal and intimately associated with OM in particles and they are difficult to separate in heavier concentrates and commonly pass to lighter fractions (clay minerals, sulfates, carbonates, and occasionally sulfides). On the other hand, the application of gravity methods for some lignites shows that the separation of minerals is relatively ineffective . Various accessory minerals of As, Au, Ba, Ce, Cl, Cr, Cu, F, Hf, La, Mn, Mo, N, P, Pb, Sb, Sn, Sr, Ti, U, V, W, Y, Zn, and Zr were identified as discrete and finely dispersed species (<10 μm) in coals by different methods. ,, Such mineral identifications were frequently performed after the application of heavy liquids separations.…”

Clay Minerals in Low-Temperature Lignite Ash

“…Artifacts are all components formed during combustion, either immediately during it (pri mary artifacts) or by crystallization of amor phous constituents and recrystallization of salts (secondary artifacts). Some cations (alka lies and iron) are bound in coal in the form of carboxyls [3,7], and most of the sulfur is pres ent in organic compounds. During combustion these ions are liberated and oxidized to x-rayamorphous compounds.…”

Analysis of the Inorganic Constituents of Particles on a Particle‐by‐Particle Basis using a Computerized SEM‐EDS System

“…Most of the reports on the application of this technique to the analysis of coal have been for the determination of organic sulfur, where the area to be analyzed is located manually. Reports on the use of an automated system are the works by Boateng and Phillips [ 5 ] , and Fowkes [6]. The presence of different elements was observed using the intensity of their radiations as the sample was moved in a straight line relative to the electron beam.…”